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Thursday, March 14, 2019

Retrospective #29: Fructose, Formerly Known as Fruit Sugar

What is fructose? Fruit sugar, right? Well, yes
and no. It is found in copious
amounts in fruit, of course, but so are other sugars. Free fructose, the
monosaccharide, is 57% of the total sugar found in an average apple, but free
glucose, another monosaccharide, is 23%. Sucrose, a disaccharide sugar,
composed of equal parts fructose and glucose, is the remaining 20%. So,
combining the free fructose with the fructose bound up in sucrose, the total
fructose in an apple is 67% of the sugars. (Trust me on the math here.) The
remaining one-third is glucose.

Apples and pears are on the high end of the fructose scale. Apricots, at 39%, are at
the low end. The sugar in bananas is 50% fructose, grapes 53%, and peaches 46%.
Honey is 50.5% fructose (free and combined). Besides tree and vine fruits
(berries), fructose is also found in other foods found in nature, for example, sweet
corn and sweet red peppers and most root vegetables (e.g., red beets, carrots,
onions and sweet potatoes). Generally, most of the fructose is bound up in
sucrose, which as we said is equal parts fructose and glucose. Sucrose in its
processed form is table sugar, which is made from refining sugar cane or sugar
beets. Table sugar is therefore 50% fructose.

According to Wikipedia, “Commercially, fructose
is usually derived from sugar cane, sugar beets and corn, and there are 3
commercially important forms:” 1) processed crystalline fructose, 2)
high-fructose corn syrup (HFCS), and 3) sucrose. HFCS is also used in baked
goods to “improve browning, for palatability and taste enhancement.”

Starting in the early 70’s, as sugar consumption
peaked in the U.S., HFCS began to erode the sucrose market. By 2000 they were
consumed in the U.S. in equal amounts. HFCS is commonly found in food and drink
in two forms: The 55% fructose/41%
glucose form is in use in the U.S. in non-dietary soft drinks. The 42%
fructose/53% glucose formulation is used primarily in processed foods and baked
goods. The balances in both forms are “other sugars.”

“The primary reasons fructose is used
commercially in foods and beverages is its low cost and its high relative
sweetness. It is the sweetest of all naturally occurring carbohydrates; at room
temperature it is 1.73 times as sweet as sucrose,” but when heated it loses
this advantage, according to Wikipedia. The
sweetness of fructose is “perceived earlier,” has a “higher peak,” and “exhibits
a synergy effect when used in combination with other sweeteners.” It has “greater
solubility,” “increases starch viscosity more rapidly, and achieves a higher
final viscosity than sucrose.” It also “retains moisture for a long period of
time even at low relative humidity,” and therefore “can contribute to improved
quality, better texture, and longer shelf life to the food products in which it
is used,” according to Wikipedia. Now you know why a Twinkie or a Devil Dog
stays soft forever. It’s the HFCS!

If you haven’t noticed how ubiquitous HFCS has
become in the processed food supply, let me give you a snapshot. In the bread
aisle at my local supermarket I found it in most of the “soft” goods and long
shelf life items: Devil Dogs and Twinkies, of course, and fruit pies and
muffins; also, in hot dog and hamburger rolls and, naturally, in Wonder Bread.
I also found it listed as 4th ingredient in Weight Watchers 100%
Whole Wheat bread, just before molasses!

Fundamentally, however, regardless of whether the
formulation of fructose you consume is 55%, 42%, or 50% fructose, as in table
sugar (sucrose), we all consume ever increasing amounts of fructose each year,
whether we know it or not. We eat much more fructose than we think, and much
more than the amount that is found in fresh fruit. Remember, sugar -- ordinary
table sugar, made from sugar cane -- is half (50%) fructose.

So, why does it matter? Because fructose, in the
words of Robert H. Lustig, MD, is “poison.” Dr. Lustig is professor of Clinical
Pediatrics in the Division of Endocrinology at the University of California San
Francisco. His research focuses on childhood obesity. He contends that, in the
amounts we are eating it, fructose is toxic to the liver.

Want to know why? You
can watch his 90-minute 2009 video, “Sugar: The Bitter Truth,” from UCSF’s
“Mini Med School for the Public” on YouTube. It’s had over 8 million views. Or
stay tuned. In the next Retrospective I will summarize Lustig’s answer to the question,
“Is Fructose a Liver Toxin.” My original post in 2011 had over 1,000 hits. And the
next, “Carbohydrates and Sugars,” about 10,000.

About Me

I was diagnosed a Type 2 diabetic in 1986. I started a Very Low Carb diet (Atkins Induction) in 2002 to lose weight. I didn’t realize at the time that it would put my diabetes in clinical remission, or that I would be able to give up almost all of my oral diabetes meds. I also didn’t understand that, as I lost weight and continued to eat Very Low Carb, my blood lipids would dramatically improve (doubling my HDL and cutting my triglycerides by 2/3rds) and that my blood pressure would drop from 130/90 to 110/70 on the same meds.
Over the years I changed from Atkins to the Bernstein Diet (designed for diabetics) and, altogether lost 170 pounds. I later regained some and then lost some. As long as I eat Very Low Carb, I am not hungry and I have lots of energy. And I no longer have any of the indications of Metabolic Syndrome.
My goal, as long as I have excess body fat, is to remain continuously in a ketogenic state, both for blood glucose regulation and continued weight loss. I expect that this regimen will continue to provide the benefits of reduced systemic inflammation, improved blood lipids and lower blood pressure as well.